Boiler for high pressure



Feb. 4, 1930.

lZOO

J. RUTHS T L BOILER FOR HIGH PRESSURE Filed Feb. 28, 1925 2 Sheets-Sheet 1 l l l l Feb. 4, 1930. Y J. RUTHS ET-AL 1,745,383

BOILER FOR HIGH PRESSURE Filed Feb. 28, 1923 2 Sheets-Sheet f If a boiler is to be'constructed to sustain for a Fatented Feb.4, 1930 I UNITED I STATES" PATENT, OFFICE JoHAriNEsfRUTHs, for DQIURSHOLM, AND urns HEZEKIEL FRENNE AND MATTIAS AcKsrRoM, oFS'rocKHoLM, SWEDEN, ASSIGNORS, BY MESNE. ASSIGNMENTS, 'ro RUTHS ACCUMULATOR .AKTIEBOLAG, or STOCKHOLM, SWEDEN, A CORPORATION BOILER ron HIGH PRESSURE Application filed-February 28, 1923, Serial No. 621,910, and in Sweden February 22, 1922.

In any boiler the main problem to be solved isto cool the gasesproduced from the fuel-to 1 suchanextent that as small a quantity of heat I as possible remains in the flue gases when 5 they leave the boiler. Now the cooling of the gases is'in the highestdegree dependent on the' coefficient ofheat'transmission between T the gases and the surface of the boiler which primarily absorbs theheat of the gases, in

10 order to transfer the heat soas to be utilized for steamproduction in some way or other. Said coefficlent of heat transmlsslonis, however, rather independent of the construction.

of the boiler. To be'sure such coefficient may beincreased within certain limits, but the relatively great difficulty of varying'the same, a causes, nevertheless, thatin any boiler con- .fstruction, operated with ordinary combustion, the steam delivery from the whole boiler, in proportion to its heat absorbing surface, will usually beanaverage of between are 6, and, in rare cases, amounting as high as 10pounds per'square foot per hour,,provided the gases of the boiler are cooled to such anextent that no -great loss due to cooling "arises. 1 f v Thus, for a' certain steam. production, a certain cooling surface for the gases, usually v necessary. Generally the heating'surface of the boiler is subjected on the other sideto the pressure of the steam and therefore, as a rule,

the entire heating surface must be sodimensioned as to sustain the highest boiler pressure. WVith the present standing of the technical art,f i t is possible, at ordinary costs, to so. construct the heating surface of a boiler i that it sustains a pressure. of 300 lbs. per

6 square inchabove atmospheric, but at higher pressure'sfthe.constructional difficulties become extraordinarily great, and consequently the costsper squarefoot will suddenlyrise at a pressure alittle above 300 lbs.- per square Y inch.

instance 1500 lbs. persquare inch, a heating surface is'necessary of the same size as that" of'aboilerof' a pressure of 300 lbs per sq. in.

called "the heating-surface of the boiler, is

structed for 1500 lbs. the costs become extraordinarily great.

The present invention has for its object, partly to reduce the surface necessary for the high pressure and to construct theheating' surface only for thepressures that are really required, and partly to provide such a structure for the part exposed to the highest pressure, as will sustain the highest pressure,

.without any risk of said parts being burnt through.

The invention consists in the boiler comprising, partly water heaters arranged be- 'hind each other and operated in series, the

water being forced therethrough step by step in such a way, that the pressure of a succeeding water heater will be higher than that of a preceding one, and partly a steam-generating part constructed for the high pressure desired, said part receiving water from the water heaters and being so constructed that the temperature on the gas side is the greatest in the Steam-generating part. I

By constructing the boiler in this manner, the heating surface for the generation of the high pressure may be considerably reduced, "thus making it possible to manufacture a highpressure boiler at moderate costs.

The inyention is illustrated in the accompanying drawing in which Figs. 1 and 2 show diagrams explaining the principle of the invention. Fig. 3 illustrates oneembodiment of the invention. The diagram according to Fig. 1 showing the heat absorption in a com- 1 mon boilerillustrates the consequence of the above described division of the boiler, afiording'the reduced heating surface of the high pressure-generating part.

In a boiler, the temperature of the gases along the heating surface passes on a logaritlr' v 11110 line, and the drop 1n temperature, to

which the gases are subjected when passing a certain area, represents approximately the heat quantity absorbed by said area. In the first parts of the boiler, however, a great heat absorption takes place by radiation, and the total quantity of heat removed from the fuel by radiation amounts usually to of the entire heating value of the fuel.

Supposing'no radiation to take place, then the initial temperature of the gases, before they havepassed any surface, would be for instance 3600 F. but on account of 25% of the heat being absorbed by radiation, an initial temperature of the gases amounting to I 2700 F is obtained, and thus the cooling curve begins at said temperature and extends from 2700 F. downwards to the point A, as shown in Fig. 1. Thus it will be found that theheating surface of the whole boiler absorbs a quantity of heat represented by the distance AB, and that for instance I the first 35% of the heating surface of the boiler have absorbed a quantity of heat represented by the length a, that is, about 72% of the heat absorbedby the whole boiler.

For that part of the heating surface which receives heat of radiation (for instance 13% of thetotal surface),.the heat absorbed is represented bythe ordinate distance between the line G-Band the dotted line C;-D, so that for instance the first 5% of the heating surface absorb a quantity of heat corresponding to the length 6 or about %.of the heat 1 absorbedby the whole boiler.

This is another proof of the old-established 'fact that the first parts ofa boiler absorb a very great portion of the heat, .whereasthe last parts absorb extraordinarily small quantities of heat, which, however, must be present to cool the gases in order to prevent excessive losses inthe flue gases.

Now it is only necessary, however, to. supply a part of the total heat absorbedby the boiler to the water underthe pressure desired,

and a great part of said heat may be supplied tothe water without formation of any steam, which circumstance may be of importance as a risk of the heating surfaces burning through is present only where steamis generated.

. In Fig. 2, these'conditi ons are further illustrated.

In this figure, two curves"'*are drawn abovethe abscissa (representing the pressure), the lower one of which curves 1n- 7 dicates the heat of liquid g of the water, when it has been heated to the boiling temperature corresponding to the pressure, while the upper curve indicates the total heat-content g' rr of dry saturated steam.

In this figure, the length 9 600 B. ,t. u.

' represents, for instance the heat of liquid at l500pounds per squareinch, and thelength r= 1200 600 600 B. t. u. represents the heat of generation of steam. 'Itis evidentfrom this diagram that theheat of generation of steam decreases with the pressure, while the f heat of liquid is increased so that for very high pressures the heat of generation of steam becomes smaller thanthe heat of liquid. .For instance, if dry saturated steam'of a'pressure of 1,500 lbs. is to be generated from water of 32 .F., it will only be necessaryto supply f about one half of the total heat for the gleneration of steam.

Now, if the bo ler is divide into a. stea generating part and a liquid-heating part, and the steam generating part is placed adjacent to the furnace, only 14% of the total heating surface are necessary for the stean1- generating part, as indicated in Fig. 1. Thus it is possible to reduce the heating surfaceofthe high pressure generating part to. such a I degree that it only amounts to 14% of the total heating surface, and, therefore,the difficulties in high pressure "generation are limited to said surface. 7

It is unfavorable, however, in economical respects, to construct the liquid heater which, according to the above, is to be built up for "86% ofthe total-surface}for the'high pressure of the steam desired, and'consequently said liquid heater is divided, according to the present invention, into several parts arranged behind each other andoperatingin series. For instance,the said boiler may be. constructed according to the invention in such manner that the water is heated in its lfirst part comprisinga suitable Water heater, to the temperature corresponding for instance to a pressure of lbs. persquare inch abso-;

lute. From thiswater heater the water is then supplied to another water 'heaterpin. which, the pressure v15,300 lbs. per, sq. in. absolute and then it is fed by means of apnmp to a water heater having a pressure of 15,00

lbs. be fin l y in roduced into the steamgenerating part. J j 7 According to Fig. 2, thereis then delivered from the 1200 B. t. u, to be supplied to every kilogram, about 220 B. t. u. in. the first. (Jontainer, 17 5 B. t. u in the water heater fora pressure of 300 lbspersq in. and about 205 B. t. u. in that for a pressure of 1.500 lbs, per sq. in. Front these figures it is evident, that 'in the steam-generating part andiinithe water water heater for a pressure of 1500 lbs. about 29%, and said two-parts together with the water heater for a pressure of 300 lbs. about 47% of the total heating. surface; The distribution of the areas will thus be as follows: 1

For thesteam-generating" part 1j&%; For-the 1500 lbs. water heater 15%; 1 V Forthe' 300 lbs. Water heater 18%;

' And for the30 t t re I V Thus the present invention brings about that on y about 29% of he total h atings rface need .besub'jected to a pressure of l500 lbs. waterheater5 3%of the lbs, only 18% to a -pressure of 50.0 lbs, While" atmospheric of. only 15 lbs r Qt 'ceursathe stsalegeneratlng garters} 153% can be cons ructed for a pressure fibQYfl instance, 1s constructed for a pressure of 800 V the Water heater forapressure of 1500 lbs.

' may be built together to one unit.

For the high'pressure part the steam generator with the water heater for the highest pressure or these parts united-constructlOIlS previously known for high pressure boilers may be used in cases where the danger of the steam-generating parts being burnt I through is eliminated, and according to the invention only a part of the boiler need be constructedas a high pressure boiler.

It will be particularly advantageous for the highpressure part to use the known construction in which a tube-coil is provided, said tube being submerged in a medium of a I relatively low steam pressure, which is high- 1y heated and ma liquid state at the temperature used, or surrounded by vapor formed by said medium, to the one end of which tube-coil water from preceding Water I heaters is supplied, thus preventing the tube y from being burnt through.

In Fig. 3, such an embodiment of the invention is shown. In this figure, c is the high pressure part, generating steam for instance of a pressure of 1500 lbs, (Z and e are water heaters, .f superheaters, g the furnace, h, j, 70 pumps, Z, we, a, 0, ;0 hot waterpipes, s

a casing for the heat-transmitting medium in the high pressurepart, and t pipes in the latter. I I

By means of the pump it, cold water is I @forced through the pipe Z into the water heater 6 which, for instance, is constructed 'for apressure of 15 lbs. above atmospheric,

the cold water being introduced at the coldest place. From thewarmest place in said water theater 0 hot water is conducted through the pipe m by means of the pump j, and through the pipe nto the water heater d which, for

lbs. per sq. in. From the warmest place thereof, water is drawn off through the pipe 39,

Y the pump 70 and the pipe 0 to the pipes of y the high pressure part, which pipes are embedded for instance in a bath of lead within j the casings 8 consisting in this case of tubes.

The high pressure-part c is located adjacent to the furnace, andion the gases having passed through said part they flow through the water heater d, the superheater f and then through the water heater 6. According to the exam ple given above, the water is heated in the last-named heater from 32 F. to a heat-content of 220 B. t.u., then in the Water heater d from 220 to 395 B. vt. u. to be supplied at v i 'last in the high pressure part 0 with so much I heat asto permit of steam beingtaken out p fromthe pipes 23. From said pipes,the steam may be fed intothe superheater f, or it may be superheated already in the pipes 25. The

i pipes 25 within the casings 8 maybe coupled in any (suitable way, and the casings may be filled with any suitable material which is of low pressure at high temperature, or other ranged as to operate permanently without a.

suction head, the water being caused 'to'flow thereto automatically; With regard to the control said pumps are preferably constructed as centrifugal pumps.

If an existing boiler plant is to be utilized the high pressure part is inserted above the grate and theold boiler is connected to said high pressure part and is used as a hot water generator.

WVhat we claim as new and desire to secure by Letters Patent of the United States of Americais-- "1. The method of generating steam which comprises adding heat to water at low pressure until the water reaches approximately the boiling point, then increasing the pressure of the water by a predetermined increment, again adding heat until the water reaches approximately the boiling point, again increasing the pressure by a predetermined increment and so continuing until the water has a pressure equalto that at which it is desired to generate steam, and then adding heat to the Water to'raise it above the boiling point and generating steam there from.

' 2; The method of generating steam which comprises heating Water in steps wherein heat is added to the water at a predetermined pressure untilthe water reaches approximately the boiling point andthen the-pressure is increased to a predetermined amount so that heat can again be added td'reachapproximately the boiling point I j 3. The method of generating steam which comprises progressively increasing heat transfer to liquid in such a manner that when the condition of the liquid approaches the boiling point due to the addition of heat, the

pressure of the liquid is increased so that ad-' ditional heat mustbe added toagain approach the boiling point, adding thisadditional heat and 'finally'adding'heat to raise the heat content to above the liquid line so that steam is generated.

4. The methodof generating, steam which comprises changing the condition of the liquid along a step' by step linelaid out on a heat content pressure .diagram' for steam showing the liquid line and saturation line which step by step line passes vertically upward at a value of low pressure until it reaches substantially the liquid line, then horizontally to a condition of higher pressure,

then upwardly until it again reaches substan-' ticnn'line 4 I meeee tielly th iqui line o contin ing unti 7 the desired pressure for generation of; steam is r eohecl WhQI th line is continued verti y upward pas t eliqnid line to t e s t ra- A. h gh pres ure bo ler mprisi g a h g pressure. s eam gen, etingsectio i ud a casing, a high temperature heat transniitting v m di m i a rela iv y low v por Pr su in 0 said ca i g, steam p p in id casing and situated in the, ap 015 sai g emp r tu e heat ransmitti g me ium, interconnected. Weten heate s f: elat vely rg ize e nnected to said high pressure seetion in series,

1 zindnieen to preve p zat n n e section compr ingdevie fo prog s y ineree ing' the. pre sure e w n t W e I heate s. T r

1 6. A high pressure boiler comprising a so elziti e y smell igh pre su steam generating secti n compos ofpipe' ,e g t perature heat-transmitting medium of a relatively low W per pressure in Which said nine v ar s uated, s id m d m g i e g5? boiling state m: he oper g mp ra ure,

inte con ec d water h at f relatively Large size eonneete l with ai h g p ssure section in. eries, nd m ans to p t po izetie Bl lGl1 B, 1T i n compr ing d iee for 1 s prngr e y lyincreasing th P s r bet n th weter heate 7 7 A 'high'pre snre boiler mp i g a high pre ure e eeln g ne e in S e i n ineluding a p ural ty of u es onne e in e serie eeeing sur ound g sa d. tu e l e metal in said casings, interconnected Water heaters t relativelylarge sizecpnnected to h gh pres e se on in ri e means in prevent. v po izetion in eo og0 tieneoxnpnie ng dev e ion-pr gre ively increasing h pres ure. bet he e Weber heaters. I I I 8- A'hgh pr esuneboil r mp is g a igh pressure steam generatingseetion including 45 pluralit fih izentally disposed tubes een eeteel ser end s nrre g d ha h endlfurneoe ge e have er o surreunding said tubes, molten metal said cas ngs, intene nne e t he e so nf rel-etii erge s z e nneoted to s id. high Pr ssure eet on eri s, and mea s to p vent vaporiz tion eac eo ion comp s ng devioee 9 progressi ely in rea nghe presence b tween the Wat r heaters- 1 5 In estim ny w reofwe e fixenr ignetunesl mime limits.

. inns FRENNE; j YMA-TTIAS BAGKSTROM- 

